Process for the sweetening of petroleum products



Un d States tm PROCESS FOR THE SWEETENING OF PETROLEUM PRODUCTS AndrGislon, Paris, and Joseph Quiquerez and Jean Daniel Maurin, GonfrevilleLOrcher, France, assignors to Compagnie Francaise de Raifiuage, SocieteAnonyme, Paris, France No Drawing. Application February 18, 1954 SerialNo. 411,256

Claims priority, application France December 12, 1953 19 Claims. Cl.208-197) The two first-mentioned applicants have established previouslythat the air oxidation of 'mercaptans which are usually contained inpetroleum products-Le. the sweetening of these products-is catalyzed byorganic chelate compounds having metallic constituents-and, inparticular, by cobalt chelates of Schifi bases resulting from thecondensation of salicylic aldehyde with a diamine.

Depending on the different methods in which the process may be carriedout, the chelates may be introduced in the fully prepared state in thepetroleum prodact to be treated, or they may be formed in situ; thedia-mine which produces the Schiff base may be aliphatic, cyclic,aromatic or hydro-aromatic. The chelate can be used in the presence of asolvent such as an alcohol, a ketone, a phenol, a fatty acid, etc., orin the form of an aqueous alcohol dispersion. In a continuous processthe product may be put in contact with an excess of chelate in such adispersion, which is recycled after separation. Or, again, one could addthe chelate solution to the prod: nct to be treated in a minimumquantity just suflicient so that the product then becomes slowly sweetin the course of storage. The oxygen dissolved in the products to betreated is often sufficient to permit the oxidation without it beingnecessary to provide for air blowing.

The present invention consists of operating the oxidation of mercaptansaccording to these techniques, which are the object of U.S. Patent No.2,659,691 and US. patent applications Serial Numbers 340,918 and 385,274filed respectively on March 6, 1953 (now US. Patent No. 2,823,173,granted February 11, 1958) and October 9, 1953, in the joint names ofAndr Gislon and Joseph Quiquerez, in the presence of a salt of lead;

The improvement which the addition of a lead salt makes possible theattainment of considerable economy "ice 2 in the presence of an aqueousalkaline solution, the function of which is essentially to neutralisethe acid liberated by the formation of the chelate.

It is not however absolutely essential that the stoichio; metricquantity of soda necessary for this neutralisation only, should beemployed and there may be, particularly in the case of continuousreactions, an excess of soda with respect to the quantity of acidliberated at any given moment.

, Or. again, the. petroleum product to which. the chelate has beenadded-either added as such or produced in sitll: by successive.additions of the Schilf base and the cobalt saltrnay be brought, if,desired, in the presence oi-a chelate solvent, into contact with analkaline sQlutiOIt, containing a lead salt, that is to say, finally.with an I alkaline solution of plumbite.

In a further alternative method, the petroleum product containing a leadsalt may he treated with an aqueous alcoholic dispersion of chelate,which may have been produced in situv in the aqueous alcoholic medium byaddition of the Sohiii base and a lead salt in a solution of adispersion agent.

The. following examples, which are not limitative, indi cate variousmethods of carrying out the process and the advantages that result fromit.

(a) Of 0.30 gram per liter ofcreso containing 10%; of lead in the formof cresolate Obtainedby diStOI iIF-LEv litharge in cresol. V

(b) Of 0.30 gram per liter of cresol containing 10% of cobalt chelate 0fdisalicylal propylene diimine-LZ.

in the amount of chelate used and facilitates the sweetening of thepetroleum products.

The process in accordance with the present invention may be applied inthe form of various alternatives which differ either in the conditionsunder which the lead salt is added to the petroleum product or to thechelated compound, either by the process of obtaining this latter, or bya particularassociation of these two factors.

The principal methods of carrying the invention into effect aredescribed below, but these indications are not to be construed aslimitations of the invention.

The lead salt may be chosen from amongst those which are soluble in thehydrocarbons: organic salt, phenolate, mercaptide, etc.

' The lead salt may be added to the hydrocarbon to be treated togetherwith the chelate in the presence of a solvent of the latter ascircumstances may require.

There may be added to the petroleum product, at the same time as thelead salt, the Schiif base and the cobalt salt which are intended to.produce in situ the chelate compound.

(c) Of 0.50 gram per liter of cresol containing 10%. of the abovechelate.

(d) Of 0.20 gram per liter of cresol containing 10% of the abovechelate.

(e) Of.0.30 gram per liter of cresol containing 6.6% of the abovechelate and 6.6% of lead.

. (f) .0f 0.30 gram per liter of cresol containing 6.6%, of the abovechelate and.10% of'lead.

All these gasolines are put in storage and those containing chelate showa progressive reduction of their mercaptan content concurrent with theformation of a precipi tate of. oxides of cobalt and/or of lead whichisreadily separated by filtration, leaving a, gasolinesubstantially freeof such metallic compounds.

Table 1 shows the development of the mercaptans after 24 hours in thevarious experiments as well as the stability of the gasolines obtainedby the different treatments in comparison to the untreated (test h) andinhibited gasoline (test g).

Table 1 Reagents, 'g./l. Content of Sass Quantity 'oisulpbu'r StabilityTests oxidized Inducby 1 g. of tion Chelate Cresol Lead Initial Afterchelate Period 24 Hrs. (Grams) (a) v 0 0. 30 0. 03 0. 024 0. 022 (b)0.03 0.30 0 0.02 1 0.003 (C) 0. 05 0. 50 0 0. 024 0. 000 (d) 0. 02 0. 200 0. 025 0. 010 (e) -0. 02 0. 30 0. 02 0. 024 0.000 0.02 0.30 0.03 0.0250.000 (9) 0 0. 30 0 0. 024 0. 024 (It) 0 0 0 0. 024 0. 024

1 The period of induction has been calculated in accordance with the Inorm A.S.T.M. No. D525-49.

. 3 One notes that lead alone is practically without effect,

that the chelate alone results in an absolute sweetening only if asufficient amount isiused, on the order of 0.05

gram per liter in the-examples studied, while the corn-:

hination chelate-lead resultsin a sweetening with a comsumption ofchelate of 0.02 gram per liter, that is, a saving of 60% as comparedwith the treatment without lead.

One also will note from the examples of Table 1 that the processimproves the inhibition of the gasoline.

EXAMPLE 2 One treats in the same manner as in Example 1, either an Iraqkerosene having a boiling range of 196 to 257" C. and a specific gravityof 0.795 or an Iraq gas oil boiling between 192 and 371 C. and'having'aspecific gravity of 0.838 with 0.30 gram per liter of crcsol containing10% bis disalicylal ethylene diimino di'cobalt and 10% of lead in theform of cresolate.

- Table 2 shows the advantage of the use of lead which results insweetening with an increased activity of the After sweetening theproducts are decolored by 1 part per thousand of active earth or by awash with 20%- sulfuric acid. The products are substantially free ofsaid metallic compounds.

EXAMPLE 3 (a) To a straight run Iraq gasoline with a boiling range of 40to 160 C. and a specific gravity of 0.720, is added 3.0 cm. per liter ofmethanol containing grams per liter of salicylal propylenediimino-cobalt.

(b) To a sample of the same gasoline is added of its volume of the samegasoline washed by the plumbite process; thus one obtains a gasoline ofwhich ,4 of the niercaptans are combined in the form of lead mercaptide.To this gasoline is added 3.0 cm. per liter of methanol containing 10grams per liter of cobalt chelate.

(c) 'To a sample of the same gasoline is added 0.014 gram per liter oflead in the form of naphthenate, then 3.0 cm. per liter of methanolcontaining 10 grams per liter of cobalt chelate.-

The products are left in storage for 24 hours, are filtered over sandand one finds that absolute sweetening has been obtained only in thecase of the gasolines treated with the cobalt chelate in the presence oflead.

This example relates to the case where the cobalt chelate is formed insitu.

To a straight run gasoline of Mid-East origin with a boiling range of 40to 200 C. and a specific gravity of 0.728 and which does not contain anyfree sulfur, is added in parallel experiments:

(a) Of 0.015 gram per liter of disalicylal propylene diimine-l,2 and0.0032 gram per liter of cobalt in the form of naphthenate.

(b) 0f 0.015 gram per liter of disalicylal propylen diimine-l,2; 0.0032gram per liter of cobalt (naphthenate) and 0.0047 gram per liter of leadin the form of mercaptide.

(c) 0f 0.015 gram per liter of disalicylal propylene diiminc-1,2; 0.0032gram per liter of cobalt (naphthenate) and 0.028 gram per liter of leadin the form of naphthenate.

After 24 hours one filters and determines the mercaptan content. Theresults shown in Table 4 underline the on the cobalt salt.

Table 4 Reagents (grams per liter) Snsn. Percent Sulphur oxidized per 1gram salicylal Cobalt After 01 chelate Lead dlimlne uaphthe- Initial 24Hrs. (grams) nate EXAMPLE 5 j The same gasoline as in Example 4 istreated by the same reagents as in Example 4, but in the presence of 25cm. per liter of 10% caustic soda. The results obtained for thequantities of reagents used are summarized in Table 5.

' Table 5 Reagents (grams per litre) Base, Percent Sulphur oxidized pergram salicylal Cobalt NaOH After of chelate Lead diirnine naph- 10%Initial 24 Hrs. (Grams) the late cmfi/l.

EXAMPLE 6 In a continuous operation one brings a gasoline--with aboiling range of 40 to 200 C. and a specific gravity of 0.730-in whichsuccessively are injected 7.5 grams per cubic meter of disalicylalpropylene diimine-1,2 and 1.6 grams per cubic meter of cobalt in theform of acetyl acetonate, in contact in a mixer with A of its volume of10% caustic soda in which are dissolved 3.5 grams per liter of litharge,while air is injected simultaneously.

The aqueous phase is separated in a settler and'irecycled to the 'mixer.

Onehas thus treated 70 liters of gasoline containing 0.025% by weight ofsulfur in the form of mercaptan with 100 cm. of caustic soda containingthe plumbite.

The gasoline obtained had a copper number of 3.

EXAMPLE 7 An aqueous dispersion of cobalt chelate of disalicylalpropylene diimine 1,2 is prepared by adding stoichiometric quantities ofcaustic, of disalicylal propylene diimine 1,2 and of cobalt nitrate to amixture of 90% by volume of water and 10% by volume of a commercialsolution of a wetting agent known as Teepol. In this manner a stableaqueous dispersion containing 1% of chelate is obtained.

One liter of straight run Iraq gasoline having a final boiling point of200 C. and a specific gravity of 0.720, containing 0.025 by weight ofsulfur in the form of mercaptan is agitated for 3 minutes with 3 cm. ofthe above mentioned dispersion of 1% chelate and is left to settle.

After 24 hours the mercaptan content has dropped to 0.012% S A parallelexperiment conducted with the same quan- EXAMPLE 8 One has prepared anaqueous alcohol solution of cobalt chelate derived from disalicylalpropylene diimine 1,2 containing 6 grams per liter of chelate and 100cm. per liter of methanol.

(1) For every 250 cm. of this solution one treats continuously in thepresence of air 70 liters of the same gasoline as in Example 7. Aftertreatment one has obtained a gasoline contaning 0.007% S In thisexperiment 1 gram of chelate has oxidized 5.4 grams of een- (2) Forevery 250 cm. of the aqueous alcohol chelate solution mentioned aboveone has treated 70 liters of the same gasoline to which previously 0.03gram per liter of lead in the form of cresolate has been added.

One has obtained in a continuous process 100 liters of gasoline with acontent of 0.000% of S and in this experiment one gram of chelate hasoxidized 12 grams Of 8353;.

All the examples given above rely on the addition of a lead salt to theproducts in reaction. However, it falls also within the scope of theinvention to employ, for the sweetening treatments considered, anequipment which includes parts or members made of lead. The applicantshave, in elfect, established that, in certain conditions of operationinvolved in carrying the process of sweetening into effect, and to whichthe invention applies, these parts or members of lead may result in theformation of a lead salt which then plays the same part as if it hasbeen added, in that form, to the products in reaction.

We claim:

1. Process for the sweetening of petroleum products by oxidation of themercaptans in the simultaneous presence of a salt of lead and of achelate of cobalt of a Schifi base resulting from the condensation of anaromatic hydroxy aldehyde with a diamine.

2. Process according to claim 1 in which the said aromatic hydroxyaldehyde is salicylic aldehyde.

3. Process according to claim 1 in which the chelate compound isintroduced in the petroleum product to be treated in the form of asolution in a solvent miscible in the petroleum product together with asalt of lead soluble in the hydrocarbons.

4. Process according to claim 1 in which the salt of lead is soluble inthe hydrocarbons.

- 5. Process according to claim 2"in'whi'cl1" the'che'l ate compound isintroduced in the petroleum'product tob'e treated in the form of asolution in a solvent miscible in the petroleum product together with asalt of lead soluble in the hydrocarbons.

6. Process according to claim 2 in which the chelate is formed in situby addition to the petroleum product of a cobalt salt soluble in thehydrocarbons and of a Schiff base resulting from the condensation of anaromatic hydroxy aldehyde with a diamine.

7. Process according to claim 2 in which the petroleum product to whichpreviously a cobalt salt of a Schiff base and a lead salt have beenadded is brought into contact with an alkaline solution.

8. Process according to claim 2 in which the petroleum product to whichpreviously a cobalt salt of a Schifi base has been added, is broughtinto contact with an alkaline solution containing a mineral salt oflead.

9. Process according to claim 2 in which the petroleum product to whicha lead salt has previously been added is treated with an aqueousdispersion of a chelate of cobalt.

10. Process according to claim 2 in which the petroleum product to whicha lead salt has previously been added is treated with an aqueousdispersion of a chelate of cobalt, prepared by the addition of a cobaltsalt and of a Schifi base to an aqueous solution of a surface activeagent.

11. Process according to claim 2 in which the petroleum product to whichpreviously has been added a lead salt is treated with an aqueous alcoholdispersion of a cobalt chelate.

12. A composition for the sweetening of petroleum products whichcomprises a mixed solution of a lead salt and cobalt chelate of a Schitfbase resulting from the condensation of an aromatic hydroxy aldehydewith a diamine.

13. A composition for the sweetening of petroleum products whichcomprises a mixed solution of a cobalt chelate compound of a Schifi baseresulting from the condensation of an aromatic hydroxy aldehyde with adiamine and a lead salt soluble in the hydrocarbons.

14. A composition for the sweetening of petroleum products whichcomprises a mixed solution of a cobalt chelate compound of a Schifi"base resulting from the condensation of an aromatic hydroxy aldehydewith a diamine and a lead salt in a solvent which is miscible with thehydrocarbons and which is selected from the class consisting ofalcohols, ketones, phenols and fatty acids.

15. A composition for the sweetening of petroleum products, comprised ofa solution, in cresol, of cresolate of lead and of chelate of cobalt ofa disalicylal-diimine.

16. For the sweetening of petroleum products, two solutions utilizedconjointly and constituted, one by a solution of a Schifi base resultingfrom the condensation of an aromatic hydroxy aldehyde on a diamine, theother by a mixed solution of two salts, one of cobalt, the other oflead, both salts being soluble in the hydrocarbons.

17. For the sweetening of petroleum products, two solutions utilizedconjointly and constituted, the one by a solution of a Schiif baseresulting from the condensation of an aromatic hydroxy aldehyde on adiamine, the said solution being rendered alkaline by a stoichiometricquantity of an alkaline hydroxide with two molecules of alkali permolecule of disalicylal-diimine, the other solution being a mixedsolution of two salts, one of cobalt, the other of lead, both saltsbeing soluble in the hydrocarbons.

18. For the sweetening of petroleum products, two solutions utilizedconjointly and constituted, the one by an alcoholic solution ofdisalicylal-diimine and alkaline alcoholate, with two molecules ofalkali per molecule of dialicylal-diimine, the other by a mixed solutionof two salts, the one of cobalt, the other of lead, both salts beingsoluble in the hydrocarbons.

19. The process of sweetening petroleum products which comprisesefiecting the oxidation of mercaptans in said products in the presenceof a free oxygen containing gas, an organicchelate compound comprised ofthe reaction product of an imino-phenol and a cobalt salt and 5 a leadsalt.

References Cited in the file of this patent UNITED STATES PATENTSBorgstrom Jan. 5, 1932 Morrell Apr. 18, 1933 Paulsen Apr. 8, 1942Gholson Dec. 1, 1942 Moulthrop Sept. 8, 1953

1. PROCESS FOR SWEETENING OF PETROLEUM PRODUCTS BY OXIDATION OF THEMERCAPTANS IN THE SIMULTANEOUS PRESENCE OF A SALT OF LEAD AND OF ACHELATE OF COBALT OF A SCHIFF BASE RESULTING FROM THE CONDENSATION OF ANAROMATIC HYDROXY ALDEHYDE WITH A DIAMINE.